Crucible-furnace



(No Model.) 2 Shets-Sheet 1.

G. NIMMO.

GRUCIBLE FURNACE.

No. 250,095. Patented Nov. 29,1881.

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G. NIMMO.

. ORUGIBLE FURNACE.-

No. 250,095. Patented Nov. 29,1881.

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If I v UNITED STATES PATENT OFFICE...

GEORGE NIMMO, OF JERSEY CITY, NEW JERSEY.

CRUCI BLE-FURNACE.

SPECIFICATION forming part of Letters Patent No. 250,095, dated November 29, 1881.

Application filed September 19, 1881. (No model.)

To all whom it may concern:

Be it known that I, GEORGE NIMMo, of J ersey City, in the State of New Jersey, have invented an Improvement in Crucible-Furnaces, of which the following is a specification.

Furnaces have been made for containing four pots or crucibles employed in the melting of steel and other metals requiring a high temperature. In furnaces of this kind it has usually been considered that the furnace could not be made practically operative when of a size to receive more than four pots, because the openings at the top for the removal of the pots would be so large as to allow too much heat to escape, to the injury of the workman engaged in handling the pots of melted metal. Besides this, the grate-bars are apt to melt down or sink under the weight, and the pots that remain in the furnace and are drawn the last are liable to become chilled in consequence of the air-blast finding its way through the fuel at the places from which the pots have been removed, and not maintaining the intensity of the combustion around the remaining pots.

My improvement is made for lessening the amount of fuel required for melting the metal, lessening the cost of the furnace, preventing injury to the men by excessive heat, and for maintaining the proper amount of air-blast to each portion of the fuel,so that the required temperature can be maintained upon all parts of thehearth and the furnace can be enlarged in size to any desired extent.

In the drawings, Figure l is a vertical section at the line 1 1. Fig. 2 is a sectional plan at the line 2 2. Fig. 3 is a vertical section at the line 3 3, and Fig. 4 is a front elevation.

The side walls, a a, are provided with airinlets or blast-pipes at b 1), opening into the ashpits c 0. The ash-pit is divided by the partition-wall d, and across this there are bearers e, the ends of which are in the walls a a and f are the grate-bars. The back wall, I, has openings at g for the escape products of combustion. These usually pass in below a steamboiler; but they may be led directly to a chimney. The front wall, m, is supported upon a bearer, n, and secured by brace-bars and tierods, as usual. There are movable stopperplates 10 to the ash-pits. At the top of the furnace the walls are drawn in, as at z, and there is an arch thrown across from the front to the back walls, as at 0, so that there are two long openings that are of a width sutficient for inserting or removing the pots or crucibles, and the covers 1 are, by preference, made of firebricks secured into iron clips, each having an eye, by which they can be lifted or moved by inserting a poker or hook into the eye.

It is found in practice that the size of the furnace is the most convenient when it can receive eight crucibles or pots for steel in each section, as shown. Thereby each furnace can have sixteen pots; but I remark that the furnaces may be duplicated or placed in a range side by side to any desired extent.

It is to be understood that in charging the furnace the fuel is introduced upon the gratebars or fire-bed to the desired thickness, the crucibles being placed in the fuel, and then the covers 1' are put in place and the blast turned on, as usual.

Economy in fuel results from the use of this furnace, because there is less of side walls to absorb and dissipate the heat in proportion to the number of pots, and the pots can be grouped closely together, as shown, so as to allow for the proper thickness offuel between the pots and the walls to maintain the desired temperature. There will be less fuel on the fuelbed with the pots arranged as shown than there would be in four separate furnaces with the same thickness of fuel between the pots and the walls. I am able to effect this saving in fuel, and at the same time insure great uniformity of tem perature, because the grate-bars are supported by the partition-wall and bearers, and are as well adapted to sustain the weight as the fire-bars that only hold four pots, I am also enabled to maintain the proper amount of air-blast, because the blast in the ash-pit at one side of the fire is separated from that at the other side; hence the air will not escape unduly through the portions of thefuel from which the pots have been removed in drawing the charge from the furnace, and the workmen are protected from the heat by the whole of the furnace being covered, except at the places where the pots are being removed. It is to be understood that the covers are shifted during the progress of removal, so as to uncover the furnace at the proper places, and that the pots are.

lifted out by the gripcrs orv tongs usually employed.

It will be evident that these furnaces may be increased in number to any desired extent, and that the hearths may open one into the. other, there being partition-walls in the ashpits and arches in the top of the furnace, instead of the partition-walls between each two hearths. The number of the pots in each furnace may be increased or lessened.

I claim as my invention- 1. The combination, in a furnace for crucibles or pots, of side walls, a fire-bed, a partition in the ash-pit that separates the same into compartments, a flue for supplying air to each compartment, escape-fines above the fire, and movable covers on the top of the furnace, substantially as set forth.

2. The combination, in a furnace for movable pots or crucibles, of the fire-bed, the side walls, the arch 0, leaving openings at each side of the arch, and the movable covers, substantially as set forth.

Signed by me this 13th day of September, A. D. 1881.

GEORGE N I MMO.

Witnesses:

B. SEYMOUR, GEORGE DONOHUE. 

